In an LED array printer, light emitted from an LED array print head is transmitted through a rod lens array onto a photosensitive drum so as to obtain an electrostatic latent image. The electrostatic latent image is then developed into a toner image by a developing unit and transferred onto paper by a transfer unit.
To form the electrostatic latent image, the photosensitive drum is charged to a predetermined potential by a charger, and irradiated with light corresponding to predetermined data.
The LED array print head includes a plurality of LED array chips and an LED driver for driving the array chips. The chips are mounted on a substrate and driven by signals transmitted between the LED array print head and a control circuit.
The control circuit for controlling the LED array print head is connected to the LED array print head through connectors and a connecting cable. The control circuit includes a logic circuit for controlling the timing of data provided to the LED print head, a CPU, memory storing therein a control program for printing, data, and the like, and a switch array for setting several kinds of modes.
The switch array is used to set parameter information relating to the specifications of the LED array print head, variations in characteristics, and the like. The CPU detects whether switches of the switch array are turned on or off and produces the parameter information, corresponding to the setting of the switches, so as to control the logic circuit.
LED array chips having a large number of divisions are used in order to increase the dot resolution so as to enhance the quality of printing. Furthermore, the number of array chips has to be increased in order to enable printing on a large size paper. However, this causes higher cost, and the power consumption increases. Accordingly, it would be desirable in general for such an LED printer to be designed to have specifications which cope with specific needs or demands.
However, should printers be specifically manufactured based on several different specifications, the manufacturing cost would soar while the time for research and development would become longer. To avoid such higher manufacturing cost and longer R&D time, a basic structure is shared with different kinds of printers, and only component parts which cannot be common are specifically designed. For example, by choosing LED array print heads and selecting several parameters for printing control, the same basic printers can have several different functions. Further, if there are variations in characteristics such as light emission or the like among the LED array print heads, uniform printing quality cannot be obtained even though LED array print heads having the same specifications are connected respectively to the control circuits, and accordingly, compensation for the variations in the characteristics must be provided while printing.
In conventional LED array printers, various functions and specifications have been obtained in the same kind of printers with the use of a switch array disposed in the control circuit, and further, variations in the characteristics of the LED array print head, have to be absorbed while printing
However, although the specifications and characteristics of an LED array print head should be known in order to manipulate the switch array, there has been no indication showing such information on the LED array print head. Further, if an LED array print head is to be replaced due to a desired change in the specifications due to a failure thereof, the switches should be reset in accordance with the specifications and characteristics of the new connected LED array print head.
Accordingly, in a conventional LED array printer, it is troublesome to set parameter data relating to the specifications and characteristics of an LED array print head in the printer control circuit, and there is also the possibility of an erroneous setting. forgetting to set or the like. Should parameter data in the control circuit be inappropriate for the connected LED array print head, the printing quality would become worse and the printer might not ever work. Further, there is the possibility of damaging the LED array print head.